Na(+) occupancy and Mg(2+) block of the n-methyl-d-aspartate receptor channel.
Na(+) occupancy and Mg(2+) block of the n-methyl-d-aspartate receptor channel.
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DOI：
10.1085/jgp.117.3.275
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发表时间：
2001-03
期刊：
影响因子：
--
通讯作者：
Auerbach A
中科院分区：
文献类型：
--
作者：
Zhu Y;Auerbach A
在重组NR 1-NR 2B NMDA受体通道上研究了细胞外和细胞内Na+对Mg ~（2+）阻断单通道动力学的影响。Na+通过占据渗透途径外部的两个位点来阻止Mg 2+进入其阻断位点。细胞内而非细胞外Na+对这些位点的占据是电压依赖性的。在没有竞争离子的情况下，Mg 2+会迅速结合（>108 M− 1 s −1，无膜电位）到距离细胞外表面电场0.60的位置。Na+占据其中一个外部位点可能足以防止Mg 2+从通道解离回到细胞外区室。无膜电位;在无竞争离子存在下，Mg ~（2+）的解离速率常数大于Mg ~（2+）渗透速率常数的10倍以上，Mg ~（2+）的平衡解离常数约为1.12 μM。细胞外Na+的生理浓度使Mg 2+结合速率常数降低了0.40倍，但由于“锁定”效应，使Mg 2+平衡解离常数仅降低了0.18倍。
The effect of extracellular and intracellular Na+ on the single-channel kinetics of Mg2+ block was studied in recombinant NR1-NR2B NMDA receptor channels. Na+ prevents Mg2+ access to its blocking site by occupying two sites in the external portion of the permeation pathway. The occupancy of these sites by intracellular, but not extracellular, Na+ is voltage-dependent. In the absence of competing ions, Mg2+ binds rapidly (>108 M−1s−1, with no membrane potential) to a site that is located 0.60 through the electric field from the extracellular surface. Occupancy of one of the external sites by Na+ may be sufficient to prevent Mg2+ dissociation from the channel back to the extracellular compartment. With no membrane potential; and in the absence of competing ions, the Mg2+ dissociation rate constant is >10 times greater than the Mg2+ permeation rate constant, and the Mg2+ equilibrium dissociation constant is ∼12 μM. Physiological concentrations of extracellular Na+ reduce the Mg2+ association rate constant ∼40-fold but, because of the “lock-in” effect, reduce the Mg2+ equilibrium dissociation constant only ∼18-fold.
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Mg（2+）块探测的N-甲基-D-天冬氨酸受体通道的K（+）占用率。
DOI：
10.1085/jgp.117.3.287
发表时间：
2001-03
期刊：
The Journal of general physiology
影响因子：
--
作者：
Zhu Y;Auerbach A
通讯作者：
Auerbach A
DOI：
10.1073/pnas.93.24.14170
发表时间：
1996-11-26
影响因子：
11.1
作者：
Sharma, G;Stevens, CF
通讯作者：
Stevens, CF
影响因子：
64.8
作者：
MAYER, ML;WESTBROOK, GL;GUTHRIE, PB
通讯作者：
GUTHRIE, PB
影响因子：
5.5
作者：
BURNASHEV, N;ZHOU, Z;SAKMANN, B
通讯作者：
SAKMANN, B
影响因子：
5.5
作者：
Wollmuth, LP;Kuner, T;Sakmann, B
通讯作者：
Sakmann, B